Object Snap to Surface Rotation

[httpDerpyy]

Hey there,

Recently I’ve worked on a simple rain system that allows for realistic rain, the drops don’t go through roofs and turn into puddles once they hit the ground.

What I’m looking forward to achieve is that, if the water drop hits a slope or an edge, it’s able to adjust its position to match the rotation of surface it’s touching.

Here’s an image to better represent.

Screenshot

The last puddle of water isn’t following the rotation of the surface it’s touching.

[markthemat3 (Markthemat)]

I am absolutely terrible at scripting but I think raycasting might help you accomplish that

[K3nism]

Try this post I don’t know if this works for slopes

@ages_dreamcast

surface normals are pretty rad
tl;dr: create a new cframe using the lookvector:cross(norm) as the rightvector, the surface normal as the upvector, and the lookvector being the same.

-- bp is the part to rotate, rcf is the old cframe (bp.CFrame in this case)
local nray = Ray.new((rcf * CFrame.new(0,bp.Size/2,0)).p,-rcf.upVector*50) -- create ray below bp (the hovercraft, humanoid you're rotating, whatever)
local rval = {workspace:FindPartOnRay(nray,bp)} -- ray to fire below
if rval[1] then -- if the ray hit a part...
  local norm = rval[3] -- surface normal of ray
  local npos = rval[2] + (norm*3) -- this is so the craft floats above the ray's pos slightly
  
  -- tcf is the new cframe thats aligned to the ground
  local tcf = CFrame.fromMatrix(npos,rcf.lookVector:Cross(norm),norm,-rcf.lookVector)
  rcf = tcf -- set craft cframe to rotated cf.
end
bp.CFrame = rcf

[Mememoxzine (zinetr1c)]

Theres this thing in RaycastResult called “Normal” (I assume you are using Raycast)

I used this to make functional bullet holes for my gun system, heres how I did it:

hole.CFrame = CFrame.new(result.Position, result.Position + result.Normal) -- result = RaycastResult

To make it actually work like intended, cause I’m using a decal, I put the decal on the front side of it. I assume you are using unions, the top of the puddle should be the Front side of the union.

[httpDerpyy]

Didn’t mark this one as a solution cause the other one, about Raycasts, was more straight forward. Thanks for the help anyways!

[Mememoxzine (zinetr1c)]

No problem man, Good luck on your project!